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Background: Mechanical alterations in patients with electrical conduction abnormalities are reported to have prognostic value in patients with left ventricular asynchrony or long QT syndrome beyond ECG variables. Whether conduction and repolarization patterns derived from ECG are associated with speckle tracking echocardiography (STE) parameters in patients without overt disease has not been previously investigated. To report ranges of longitudinal deformation according to conduction and repolarization values in a population-based cohort. In total, 1140 subjects (48.6 ± 14.0 years,) enrolled in the STANISLAS cohort were studied. Echocardiography with layer-specific strain was performed in all subjects. RR, PR, QRS and QT intervals were retrieved from digitalized twelve-lead ECG. Echocardiographic data were stratified according to quartiles of QRS and QTc duration values. Full-wall peak longitudinal strain (PLS) was −21.1% ± 2.5% with a mechanical dispersion value of 33.6 ± 11.7ms. Absolute PLS value was lower in the longest QRS quartile and shortest QTc quartile (both P < 0.001). Time-to-peak of strain was not significantly different according to QRS duration although significantly higher in patients with higher QTc (P < 0.001). Mechanical dispersion was significantly greater in patients with longer QTc (32.45 ± 11.68 ms for QTc < 396 ms versus 35.88 ± 11.94 ms for QTc > 421ms; P = 0.002). QTc is associated with variations in normal values of the deformation pattern of longitudinal systolic strain such that mechanical dispersion and QTc-specific normal values should preferentially be used. In a population-based setting, QRS is not associated with mechanical dispersion suggesting that echocardiography-based dyssynchrony does not largely overlap with ECG-based dyssynchrony. [ABSTRACT FROM AUTHOR]